Kelvin-Helmholtz Vortex Formation and Particle Transport in a Cross-Field Plasma Sheath

The time-dependent behavior of a magnetized, two-dimensional plasma-wall sheath has been studied through particle simulations, which have shown that the cross-field sheath develops into a turbulent boundary layer, driven by the Kelvin-Helmholtz instability. The sheath acquires an equilibrium thickness lₓ~5ρᵢ, and maintains long-lived vortices, with amplitudes δφ~-2Tᵢe, which drift parallel to the wall at half the ion thermal velocity. A central simulation result is that for ωₚᵢ≥2ωci, the anomalous particle transport in the sheath scales like Bohm diffusion.